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The development of a coarse grained microstructure during the recrystallization has been noted and discussed by a number of authors but, the mechanism of grain control remains uncertain.
It appears that two factors: the peculiar distribution of high- (HAGB) and low- (LAGB) angle grain boundaries in the as-consolidated state, and the uniformity of the fine scale microstructure makes the nucleation of recrystallization difficult because the grain boundary junctions are strong pinning points, restricting the bowing of grain boundaries [7].
The grain structures in the tensile and compressed areas of sample 4 are presented in Fig.5.
It should be emphasized that the sub-micron grains are not low-misorientation cell structures typical in aluminum alloys, but true grains with large misorientations (see Fig. 5).
Subsequent heat-treatment leads to recrystallization into a very coarse grained microstructure [4].

The CNA method uses a ternary number, ijk to denote an inter-atomic bond.
In the ternary number system, i designates the number of common neighbors shared by two atoms, j denotes the number of bonds among those common neighbors, and k indicates the longest path in these bonds.
Within the grain size regime investigated, the yield stress increases with increasing grain size, revealing an inverse Hall-Petch effect.
A number of theories have been proposed to explain the Hall-Petch break-down[18], a recent argument put forward by Louchet [19] and co-workers seems particularly appealing.
However, a peak fraction exists for each grain size with the actual peak value depending on the initial grain size.

The TiAl alloy with fine grain via reactive sintering was obtained.
The microstructure of TiAl intermetallic alloy shows equiaxed grain that the average grain size is 5~10µm (Fig.8).
The grain size of TiAl alloy has been grown slightly but the shape of the grain is not changed.
The grain size is average 8µm.
Acknowledgements This work was supported by the Postdoctoral Foundation of Heilongjiang Province under grant number AUGA41000551.

In addition, recovery influences precipitation through its effect on the number of potential precipitate nucleation sites (i.e. number of dislocations).
An indirect effect of precipitation is to deplete Nb form solid solution leading to a reduction in the solute drag the Nb exerts on the grain-boundaries of the recrystallizing grains.
The number of dislocation nodes, nc, was approximated as 0.5ρ1.5.
A number of authors have shown that the Zener approach, or a modified version of it, accurately captures the effect of a stable particle distribution on the growth of the recrystallizing grains [12, 16-18].
Accelerated coarsening of the particles located at the grain boundary will lead to a local reduction in the pinning force and the boundary is able to advance (locally) until it encounters a sufficient number of fresh particles which will ensure that the boundary is pinned again.

Table 1: Constants for copper grains ([27]).
It is seen in Fig. 3 that the nonhomogeneous part for the coarse grain size is small but when the grain size approaches to nonometer ranges, this part becomes dominant.
However, for simplicity, the strain gradient are computed here based on the directional derivative as: Dnf = ▽f.n (15) where n is the unit direction between the points and ▽f is: ▽ f = ∂f ∂xi + ∂f ∂y j (16) In Eq. 15, for the N number of nearest points around the interest point i, strain gradients are calculated.
It is demonstrated that for micro size grains, this effect is too low.
However, for 49 nm grain size, the difference is noticeable.

Experimental Investigation of Brittle to Ductile Transition of Single Crystal Silicon by Single Grain Grinding F.W.
Grinding is a very complex manufacturing process which is involved with a great number of variables, such as wheel type, wheel condition, operating parameters, coolant condition and machine characteristics.
conducted single grain grinding experiments on a modified wafer grinding machine [6].
Fig. 3 3D image of single grain grinding groove shown in Fig. 2(b) Material response based on subsurface damage.
Therefore, below a critical depth of cut, cracks will fail to form around the cutting grain.

These monolithic technologies are used to reduce part count as well as the number of fasteners, assembly time, and weight all of which lead to cost savings for the product.
Even though either of these processes would allow the number of components to be reduced by combining details, it was decided to keep the same number of major parts.
A fine grain version of 6Al-4V, with a grain size of about 1 µm, has been jointly developed by Verknaya Salda Metallurgical Production Association, VSMPO, in Russia and Boeing.
This fine grain material will also diffusion bond to standard grain alpha-beta alloys, as shown in Fig. 5, at 775°C using the same time and pressure conditions.
Fig. 6 Representative SPF heat shield details produced using fine grain 6Al-4V.

The results have indeed shown that IFC can shorten the HP and reduce austenite grain growth and its variation across thick plate.
This technique has been successfully adopted in a number of industrial plate mills.
The prior austenite grain sizes from the as-quenched PSC samples were revealed by etching in saturated picric acid and grain sizes were measured by the linear intercept method.
Fifthly, the steel B with Ti and Nb microalloying elements had the finest prior austenite grain size after 3 roughing passes, as shown in the Fig. 5, which indicates that the Ti restricted the austenite grain growth during the high temperature deformation.
The refinement of austenite grain size is due to the IFC lowered austenite grain growth temperature and to a much shorter waiting time during the HP.

In addition, Ta element has effect on grain refinement and the number of γ′-Co3(Al,W) phase refines grain.
Cobalt, Tungsten, Aluminum, Tantalum powders purity and grain size are 99.95%, 99.96%, 99.5%, 99.9%, -300, -200, -325 and -200 meshes, respectively.
The 9.8W alloy grain is strips, but the grains of 2Ta alloy is ball rod along, and a large number of white particles at grain boundary precipitation on the matrix, the precipitation is γ'-Co3(Al,W) phase or A3B-type phase, which cannot be determined.
(2) Addition of alloying elements Ta can increase the number of γ' phase and refine grains of Co-8.8Al-9.8W superalloy, the high temperature properties of Co-Al-W superalloy is improved

The corrosion potential and rate of depended on the feed direction and number of pass. 1.
As shown in Fig. 4-(b), route-A produces grains with high angle grain boundary.
The micro-hardness increases from 75 Hv to 190-210 Hv with increasing number of pass.
Deformation bands were more clearly observed as number of feeding increases.
Route-A produced grains with high angle grain boundary.